Expanding cam lock for sealing slab gels in an electrophoresis apparatus

ABSTRACT

An expanding cam lock for use with an electrophoresis system is disclosed herein. In one example embodiment, the expanding cam lock includes a base plate with a first surface adapted to engage the first buffer core assembly and a follower plate having second surface adapted to engage the second buffer core assembly, buffer dam or buffer displacement dam. The base plate and the follower plate are slidably coupled together and are designed for insertion between the first buffer core assembly and the second buffer core assembly, buffer dam or buffer displacement dam in the electrophoresis container. A cam is positioned between and moveably coupled with the base plate and the follower plate. The cam is movable from a first position to a second position to urge the first and second surfaces to secure the gel cassette to the first and second buffer core assemblies.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation application claims the benefit of U.S.application Ser. No. 11/404/985, filed Apr. 14, 2006, now issued as U.S.Pat. No. 8,092,665 on Jan. 10, 2012, which claims the benefit of U.S.Provisional Application Ser. No. 60/671,757, filed on Apr. 15, 2005, andU.S. Provisional Application Ser. No. 60/711,919, filed on Aug. 25,2005, all of which are commonly owned with this application and thedisclosures of which are hereby expressly incorporated by reference intheir entirety as though fully set forth herein.

TECHNICAL FIELD

The present invention relates generally to an apparatus for performingelectrophoresis. More particularly, the present invention relates to anexpanding cam lock for clamping and sealing slab gel cassettes in a gelelectrophoresis system during electrophoresis. The present inventionalso relates to a displacement dam for use in a gel electrophoresisapparatus or an electrophoretic transfer apparatus that occupies spacein a buffer chamber of the apparatus such that less volume of buffer isrequired than would otherwise be used. A displacement dam isparticularly useful when performing electrophoresis using fewer than themaximum number of gel cassettes than can be accommodated by theelectrophoresis apparatus or electrophoretic transfer(“electroblotting”) apparatus.

BACKGROUND

Gel electrophoresis is commonly used to separate, by molecular size,biological molecules, such as deoxyribonucleic acid (“DNA”), ribonucleicacid (“RNA”) and proteins. To perform gel electrophoresis, a polymericgel, such as polyacrylamide, is formed in a glass tube, or betweenspaced glass or plastic plates. The tube or plates are then placed in acontainer along with anode and cathode elements at the top and bottom ofthe gel. Sample wells formed in the top of the gel are first filled withbuffer solutions. Molecule samples prepared in a sample buffer that maycontain a tracking dye are then placed in the wells. Electrophoreticbuffer solutions containing conductive ions are added to the containerto make electrical contact between the gel, the samples in the wells andthe anode and cathode elements. A voltage is then applied across thegel, which causes the sample molecules and any tracking dye to migratetoward the bottom of the gel, and separate into bands whose migrationdistance depends on molecular size.

For accurate electrophoretic separation, the first and second buffersolutions must be isolated from one another. To provide isolation,electrophoresis systems use various methods to hold the gel cassettes incontact with the buffer core and secure the buffer core assembly in thecontainer. Previously known electrophoresis systems commonly use abuffer core subassembly containing clamps or latches that secure the gelcassettes to the buffer core.

Gel electrophoresis systems, such as the XCell SureLock™ Mini-Cellsystem manufactured by Invitrogen Corporation, of San Diego, Calif., orthe electrophoresis system described in U.S. Pat. No. 6,001,233, includea container for receiving a first buffer solution and a buffer coreassembly for receiving a second buffer solution. The buffer coreassembly comprises a pair of gel cassettes affixed to front and backsides of a U-shaped buffer core body forming a buffer core assembly. Thespace defined by the upraised side members of the buffer core body andthe end faces of the gel cassettes forms an upper buffer chamber. Oncethe cassettes are secured, the buffer core assembly is loaded in theelectrophoresis container toward one end prior to electrophoreticseparation. A cam-activated clamp is then inserted into anelectrophoresis container near the other end, between the buffer coreassembly and the back wall of the container. A cam on the cam-activatedclamp is disposed to engage a back wall of the container to cause amounting block to apply uniform pressure to secure the gel cassettes tothe buffer core body. Since there is only one mounting block, thiselectrophoresis system is limited to one buffer core assembly with amaximum of two gel cassettes. If a second buffer core assembly ispositioned on the cam side of the cam activated clamp, the cam maydeform the gel cassette in contact with the cam, and this deformation ofthe gel cassette may allow leakage of the buffer solution from the upperbuffer chamber in the second buffer core assembly.

In view of the practical limitations associated with prior art clampingmethods and apparatus, it is desirable to provide a cam-activated lockthat requires no clamping subassembly and is positioned between twobuffer core assemblies to reliably secure electrophoresis gel cassettesin each of the buffer core assemblies. It is further desirable toprovide a cam-activated lock that provides a consistent and reproducibleclamping force each time the apparatus is used.

Another issue for users of gel electrophoresis apparatuses that canaccommodate multiple buffer cores is the unnecessary use of largevolumes of buffer when fewer than the maximum number of gels are run inthe apparatus.

Furthermore, in certain aspects, provided herein is an apparatus forelectrophoresis or electrophoretic transfer of biomolecules that thatincludes a buffer displacement dam in at least one buffer reservoir ofthe apparatus. The buffer displacement dam is a solid or partially orsubstantially hollow or open structure that conforms to the size of theinterior of the buffer reservoir in at least one dimension, and replacesthe space which would otherwise be occupied by buffer contained withinthe buffer reservoir during electrophoretic separation or transfer ofbiomolecules.

SUMMARY OF THE INVENTION

An expanding cam lock is described herein for simultaneously running aplurality of gels or electrophoretic strips, including but not limitedto slab gels and slab gel cassettes, in buffer core assemblies within anelectrophoresis system while maintaining the necessary compressive forceto create a liquid-tight seal in the buffer core assemblies to keep theanode and cathode buffer solutions separate.

An aspect of the expanding cam lock described herein, used for sealingat least one gel cassette in an electrophoresis apparatus, is anexpanding cam lock which comprises a base plate having a first surfaceadapted to engage a buffer core assembly comprising at least oneelectrophoresis gel cassette; a follower plate having a second surfaceadapted to engage a partition assembly, and a cam positioned between andmoveably coupled with the base plate and the follower plate; wherein,the base plate and the follower plate are slideably coupled together andconfigured for insertion between the buffer core assembly and thepartition assembly in the electrophoresis apparatus, and the cam beingmovable from a first position to a second position to urge the firstsurface toward the electrophoresis gel cassette of the buffer coreassembly and the second surface toward the partition assembly therebysealing at least one electrophoresis gel cassette to the buffer coreassembly within the electrophoresis apparatus.

In an embodiment of this aspect, the partition assembly comprises abuffer dam, a buffer displacement dam, or a buffer core assemblycomprising at least one electrophoresis gel cassette. In a further oralternative embodiment, the cam is pivotally coupled to the base plateand is configured to slideably engage the follower plate. In a furtheror alternative embodiment, the cam includes axle pins pivotally couplingthe cam to the base plate. In a further or alternative embodiment, thecam is configured to lock the base plate into engagement with theelectrophoresis gel cassette of the buffer core and the follower plateinto engagement with the partition assembly when the cam is in thesecond position. In a further or alternative embodiment, the camincludes a push bar configured to engage the base plate to preventfurther urging of the first surface toward the buffer core assembly andthe second surface toward the partition assembly. In a further oralternative embodiment, the cam includes a handle to pivot the camrelative to the base plate and follower plate. In a further oralternative embodiment, the cam further has a curved end that slidinglyengages the follower plate. In a further or alternative embodiment, thefirst and second surfaces include push tabs adapted to facilitate urgingof the first surface toward the buffer core assembly and the secondsurface toward the partition assembly. In a further or alternativeembodiment, the base plate includes first side panels on a reverse sideopposing the first surface and the follower plate includes second sidepanels on a reverse side opposing the second surface, the first andsecond side panels being coupled together. In a further or alternativeembodiment, the first side panels include slots and the second sidepanels include lever arms with locking portions configured to slideablyengage the slots.

In further or alternative embodiments, the base plate, follower plate,partition assembly, and cam are made of a polymer selected from thegroup consisting of styrene acrylonitrile, polycarbonate, polystyrene,acrylic, acrylate, polymethyl methacrylate, polyethylene, high densitypolyethylene, polyethylene terephthalate, glycol-modified polyethyleneterephthalate, polypropylene, polyoxymethylene, Acetel and copolymersthereof. In further or alternative embodiments, the base plate, followerplate, partition assembly, and cam are fabricated by a moldingtechnique. In a further or alternative embodiment, the molding techniqueis injection molding. In a further or alternative embodiment, the baseplate, follower plate, partition assembly, and cam are fabricated bymachining.

In an aspect of the expanding cam described herein is an expanding camlock for sealing gel cassettes in first and second buffer coreassemblies in an electrophoresis container, wherein the expanding camlock includes a base plate having a first surface adapted to engage thefirst buffer core assembly; a follower plate having second surfaceadapted to engage the second buffer core assembly, the base plate andthe follower plate being slideably coupled together and configured forinsertion between the two buffer core assemblies in the electrophoresiscontainer; and a cam positioned between and moveably coupled with thebase plate and the follower plate, the cam being movable from a firstposition to a second position to urge the first and second surfaces tosecure the gel cassettes to the first and second buffer core assemblies.

In a further or alternative embodiment, the cam of the expanding camlock is pivotally coupled to the base plate and is configured toslideably engage the follower plate, while in a further or alternativeembodiment, the cam includes axle pins pivotally coupling the cam to thebase plate. In a further or alternative embodiment, the cam isconfigured to lock the base plate and follower plate into engagementwith the gel cassettes of the buffer core assemblies when the cam is inthe second position. In a further or alternative embodiment, the camincludes a push bar configured to engage the base plate to preventfurther urging of the first and second surfaces toward the first andsecond buffer core assemblies. In a further or alternative embodiment,the cam includes a handle to pivot the cam relative to the base plateand follower plate. In a further or alternative embodiment, the camfurther has a curved end that slidingly engages the follower plate. In afurther or alternative embodiment, the first and second surfaces includepush tabs adapted to facilitate urging of the first and second surfacesagainst the first and second buffer core assemblies. In a further oralternative embodiment, the base plate includes first side panels on areverse side opposing the first surface and the follower plate includessecond side panels on a reverse side opposing the second surface, thefirst and second side panels being coupled together, while in a stillfurther or alternative embodiment, such a first side panels includeslots and the second side panels include lever arms with lockingportions configured to slideably engage the slots.

In further or alternative embodiments, the base plate, follower plate,and cam are made of plastic selected from the styrene acrylonitrile(SAN), polyurethane, polyvinylchloride (PVC), polycarbonate, polystyrene(PS), acrylic-based polymers, nylon based polymers,polymethylmethacrylate (PMMA), polyethylene terephthalate (PET),glycol-modified polyethylene terephthalate (PETG), polypropylene (PP),cyclo-olefin polymer (COP), polyphenylene ether (PPE), polyoxymethylene(POM), and copolymers thereof. Other representative materials that canbe used to fabricate the expanding cam lock described herein include,but are not limited to epoxy based polymers, cyclo-olefin copolymer(COC), polychlorotrifluoroethylene (PCTFE), polyetheretherketone (PEEK),polyetherimide (PEI), polyethersulfone (PES), polyethylene (PE), highdensity polyethylene (HOPE), low density polyethylene (LDPE),polyethylene naphthalate (PEN), polyester, polyhydroxybutyrate (PHB),polyhydroxyvalerate copolymer, polyimide (PI), polyoxymethylenecopolymer (POMC), polyoxymethylene copolymer (POMC), polyoxymethylenehomopolymer (POMH), polyphenyleneoxide (PPO), polyphenylenesulfide(PPS), polyphenylsulfone (PPSu), polystyrol, polysulphone (PSu),polytetrafluoroethylene (PTFE), polyvinyl fluoride (PVF),polyvinylidenechloride (PVDC), polybutyleneterephthalate (PBT),fluorinated ethylenepropylene (FEP), perfluoralkoxyalkane (PFA), andpolyvinylidenefluoride (PVDF) and copolymers thereof.

In further or alternative embodiments, the base plate, follower plate,and cam are fabricated by molding techniques, hot embossing methods,casting processes, thermoforming methods, stereolithography processes,machining methods and milling processes. In further or alternativeembodiments, the base plate, follower plate, and cam are fabricated byinjection molding. In further or alternative embodiments, the baseplate, follower plate, and cam are fabricated by compression molding. Infurther or alternative embodiments, the base plate, follower plate, andcam are fabricated by machining.

In another aspect of the expanding cam lock described herein is anexpanding cam lock for securing electrophoresis gel cassettes to firstand second buffer core assemblies in an electrophoresis container,wherein the container has a first end wall defining a first recess and asecond end wall defining a second recess, and the first buffer coreassembly is disposed in the container proximate the first end wall andthe second buffer core assembly is disposed in the container proximatethe second end wall. Also, the expanding cam lock includes a base platehaving a first surface adapted to engage the first buffer core assemblyand first side panels on the reverse side of the first surface, afollower plate having a second surface adapted to engage the secondbuffer core assembly and second side panels on the reverse side of thesecond surface, the first and second side panels being slideably coupledand the base plate and follower plate being configured for insertionbetween the first and second buffer core assemblies and a cam pivotallycoupled to the base plate, the cam slidingly engaging the follower plateto urge the first surface to secure one or more gel cassettes in thefirst buffer core assembly and the second surface to secure one or moregel cassettes in the second buffer core assembly.

In a further or alternative embodiment, the cam is configured to lockthe base plate and the follower plate into engagement with the gelcassettes of the first and second buffer core assemblies. In a furtheror alternative embodiment, the first side panels of the mounting blockinclude axle bushings. In a further or alternative embodiment, the camincludes axle pins pivotally coupled in the axle bushings. In a furtheror alternative embodiment, the first side panels include slots and thesecond side panels include lever arms with locking portions configuredto slideably engage with the slots. In a further or alternativeembodiment, the cam includes a push bar configured to engage the baseplate to prevent further urging of the first and second surfaces towardthe first and second buffer core assemblies. In a further or alternativeembodiment, the cam includes a handle to pivot the cam relative to thebase plate and follower plate. In a further or alternative embodiment,the cam further has a curved end that slidingly engages the followerplate. In a further or alternative embodiment, the first and secondsurfaces include push tabs adapted to facilitate urging the first andsecond surfaces against the first and second buffer core assemblies.

Another aspect described herein is a method for securing first andsecond buffer core assemblies having electrophoresis gel cassettes in anelectrophoresis container using the expanding cam described herein. In afurther or alternative embodiment, the method involves obtaining a baseplate having a first surface adapted to engage the first buffer coreassembly and a follower plate having second surface adapted to engagethe second buffer core assembly. The follower plate is slideably coupledto the base plate and a cam is positioned between, and moveably coupledwith, the base plate and the follower plate. The base plate, thefollower plate and the cam are inserted between the first and secondbuffer core assemblies in the electrophoresis container. The cam ismoved from an open position to a closed position to urge the first andsecond surfaces to secure the gel cassettes to the first and secondbuffer core assemblies. In a further or alternative embodiment, movingthe cam to the closed position causes the cam to lock the base plate andthe following plate into engagement with the gel cassettes of the firstand second buffer core assemblies.

In another aspect of the expanding cam described herein areelectrophoresis kits which include, but are not limited to, anelectrophoresis container having a first end wall defining a firstrecess and a second end wall defining a second recess; at least onebuffer core assembly; and an expanding cam lock. The expanding cam ofwhich includes, but is not limited to, a base plate having a firstsurface adapted to engage a buffer core assembly and having first sidepanels on the reverse side of the first surface; a follower plate havinga second surface adapted to engage a partition assembly and havingsecond side panels on the reverse side of the second surface, the firstand second side panels being slideably coupled and the base plate andfollower plate being configured for insertion between the first buffercore assembly and the partition assembly; and a cam pivotally coupled tothe base plate and the cam slidingly engaging the follower plate.

In further or alternative embodiment, the partition assemblies of suchkits are selected from a buffer dam, a buffer displacement dam, or abuffer core assembly comprising at least one electrophoresis gelcassette. In further or alternative embodiment, at least one of theelectrophoresis container, the base plate, the follower plate, the cam,the partition assembly or the buffer core assembly is made of a polymerselected from the group consisting of styrene acrylonitrile,polycarbonate, polystyrene, acrylic, acrylate, polymethyl methacrylate,polyethylene, high density polyethylene, polyethylene terephthalate,glycol-modified polyethylene terephthalate, polypropylene,polyoxymethylene, Acetel and copolymers thereof. In further oralternative embodiment, at least one of the electrophoresis container,the base plate, the follower plate, the cam, the partition assembly orthe buffer core assembly is fabricated by a molding technique. Infurther or alternative embodiment, the molding technique is injectionmolding. In further or alternative embodiment, at least one of theelectrophoresis container, the base plate, the follower plate, the cam,the partition assembly or the buffer core assembly is fabricated bymachining.

In further or alternative embodiment, the cam includes axle pinspivotally coupling, the cam to the base plate. In further or alternativeembodiment, the cam is configured to lock the base plate into engagementwith the electrophoresis gel cassette of the buffer core and to lock thefollower plate into engagement with the partition assembly when the camis in the second position. In further or alternative embodiment, the camincludes a push bar configured to engage the base plate to preventfurther urging of the first surface toward the buffer core assembly andthe second surface toward the partition assembly. In further oralternative embodiment, the cam includes a handle to pivot the camrelative to the base plate and follower plate. In further or alternativeembodiment, the cam further has a curved end that slidingly engages thefollower plate. In further or alternative embodiment, the first andsecond surfaces include push tabs adapted to facilitate urging of thefirst surface toward the buffer core assembly and the second surfacetoward the partition assembly. In further or alternative embodiment, thefirst side panels include slots and the second side panels include leverarms with locking portions configured to slideably engage the slots.

In another aspect of the expanding cam described herein areelectrophoresis assemblies which include an electrophoresis containerhaving a first end wall defining a first recess and a second end walldefining a second recess; a buffer core assembly disposed in thecontainer proximate the first end wall; a partition assembly disposed inthe container proximate the second end wall; and an expanding cam lockfor sealing at least one electrophoresis gel cassette to the buffer coreassembly.

In a further or alternative embodiment, the expanding cam lock includesa base plate having a first surface adapted to engage the buffer coreassembly and having first side panels on the reverse side of the firstsurface; a follower plate having a second surface adapted to engage thepartition assembly, and having second side panels on the reverse side ofthe second surface, the first and second side panels being slideablycoupled and the base plate and follower plate being configured forinsertion between the buffer core assembly and the partition assembly;and a cam pivotally coupled to the base plate and the cam slidinglyengaging the follower plate to urge the second surface toward thepartition assembly and to urge the first surface to secure one or moreelectrophoresis gel cassettes in the first buffer core assembly. In afurther or alternative embodiment, the partition assemblies of suchelectrophoresis assemblies are selected from buffer dam, a bufferdisplacement dam, or a buffer core assembly comprising at least oneelectrophoresis gel cassette.

In further or alternative embodiments, at least one of theelectrophoresis container, the base plate, the follower plate, the cam,the partition assembly or the buffer core assembly is made of a polymerselected from the group consisting of styrene acrylonitrile,polycarbonate, polystyrene, acrylic, acrylate, polymethyl methacrylate,polyethylene, high density polyethylene, polyethylene terephthalate,glycol-modified polyethylene terephthalate, polypropylene,polyoxymethylene, Acetel and copolymers thereof. In further oralternative embodiments, at least one of the electrophoresis container,the base plate, the follower plate, the cam, the partition assembly orthe buffer core assembly is fabricated by a molding technique. Infurther or alternative embodiments, the molding technique is injectionmolding. In further or alternative embodiments, at least one of theelectrophoresis container, the base plate, the follower plate, the cam,the partition assembly or the buffer core assembly is fabricated bymachining.

In a further or alternative embodiment, the cam includes axle pinspivotally coupling the cam to the base plate. In a further oralternative embodiment, the cam is configured to lock the base plateinto engagement with the electrophoresis gel cassette of the buffer coreand to lock the follower plate into engagement with the partitionassembly when the cam is in the second position. In a further oralternative embodiment, the cam includes a push bar configured to engagethe base plate to prevent further urging of the first surface toward thebuffer core assembly and the second surface toward the partitionassembly. In a further or alternative embodiment, the cam includes ahandle to pivot the cam relative to the base plate and follower plate.In a further or alternative embodiment, the cam further has a curved endthat slidingly engages the follower plate. In a further or alternativeembodiment, the first and second surfaces include push tabs adapted tofacilitate urging of the first surface toward the buffer core assemblyand the second surface toward the partition assembly. In a further oralternative embodiment, the first side panels include slots and thesecond side panels include lever arms with locking portions configuredto slideably engage the slots.

In another aspect described herein is an apparatus for electrophoresisor electrophoretic transfer of biomolecules that comprises a bufferdisplacement dam in at least one buffer reservoir of the apparatus,wherein the buffer displacement dam conforms to the size of the interiorof the buffer reservoir in at least one dimension, and wherein thebuffer displacement dam replaces buffer that would otherwise becontained within the buffer reservoir during electrophoretic separationor transfer of biomolecules. In further or alternative embodiments, thebuffer displacement dam comprises a bottom and at least three sides. Infurther or alternative embodiments, the buffer displacement damcomprises a bottom and at least four sides. In further or alternativeembodiments, the buffer displacement dam is solid. In further oralternative embodiments, the buffer displacement dam is partially orsubstantially hollow. In further or alternative embodiments, the atleast four sides of the buffer displacement dam define an interiorspace. In further or alternative embodiments, the buffer displacementdam comprises one or more interior support structures. In further oralternative embodiments, the aid buffer displacement dam replaces avolume of buffer equal to at least 10% of the total volume of the atleast one buffer reservoir. In further or alternative embodiments, thebuffer displacement dam replaces a volume of buffer equal to at least20% of the total volume of the at least one buffer reservoir. In furtheror alternative embodiments, the buffer displacement dam replaces avolume of buffer equal to at least 30% of the total volume of the atleast one buffer reservoir. In further or alternative embodiments, thebuffer displacement dam resplaces a volume of buffer equal to at least40% of the total volume of the at least one buffer reservoir.

In further or alternative embodiments, the buffer displacement damcomprises one or more polymers or copolymers selected from the styreneacrylonitrile (SAN), polyurethane, polyvinylchloride (PVC),polycarbonate, polystyrene (PS), acrylic-based polymers, nylon basedpolymers, polymethylmethacrylate (PMMA), polyethylene terephthalate(PET), glycol-modified polyethylene terephthalate (PETG), polypropylene(PP), cyclo-olefin polymer (COP), polyphenylene ether (PPE),polyoxymethylene (POM), and copolymers thereof. Other representativematerials that can be used to fabricate the expanding cam lock describedherein include, but are not limited to epoxy based polymers,cyclo-olefin copolymer (COC), polychlorotrifluoroethylene (PCTFE),polyetheretherketone (PEEK), polyetherimide (PEI), polyethersulfone(PES), polyethylene (PE), high density polyethylene (HDPE), low densitypolyethylene (LDPE), polyethylene naphthalate (PEN), polyester,polyhydroxybutyrate (PHB), polyhydroxyvalerate copolymer, polyimide(PI), polyoxymethylene copolymer (POMC), polyoxymethylene copolymer(POMC), polyoxymethylene homopolymer (POMH), polyphenyleneoxide (PPO),polyphenylenesulfide (PPS), polyphenylsulfone (PPSu), polystyrol,polysulphone (PSu), polytetrafluoroethylene (PTFE), polyvinylfluoride(PVF), polyvinylidenechloride (PVDC), polybutyleneterephthalate (PBT),fluorinated ethylenepropylene (FEP), perfluoralkoxyalkane (PFA), andpolyvinylidenefluoride (PVDF) and copolymers thereof.

In further or alternative embodiments, the buffer displacement dam maybe fabricated by molding techniques, hot embossing methods, castingprocesses, thermoforming methods, stereolithography processes, machiningmethods and milling processes. In further or alternative embodiments,the base plate, follower plate, and cam are fabricated by injectionmolding. In further or alternative embodiments, the buffer displacementdam may be fabricated by compression molding. In a further oralternative embodiment, the buffer displacement dam may be fabricated bymachining.

In a further or alternative embodiment, the apparatus is anelectrophoretic gel blotting apparatus. In further or alternativeembodiments, the electrophoretic gel blotting apparatus includes abuffer reservoir in the form of a buffer tank that includes at least onegel cassette used for electrophoretic transfer of biomolecules. Infurther or alternative embodiments, the at least one gel cassette issmaller than the maximum size of gel cassette that the electrophoreticgel blotting apparatus can accommodate. In further or alternativeembodiments, the gel blotting apparatus is designed to accommodatemultiple gel cassettes. In further or alternative embodiments, theelectrophoretic gel blotting apparatus comprises fewer than the maximumnumber of gel cassettes it is designed to accommodate.

In further or alternative embodiments, the apparatus is a gelelectrophoresis apparatus. In further or alternative embodiments, thegel electrophoresis apparatus includes at least one gel or gel cassetteused for electrophoretic separation of biomolecules. In further oralternative embodiments, the apparatus comprises fewer than the maximumnumber of gels or gel cassettes it is designed to accommodate. Infurther or alternative embodiments, the buffer displacement dam replacesthe space otherwise occupied by cathode buffer. In further oralternative embodiments, the buffer displacement dam replaces the spaceotherwise occupied by anode buffer.

In further or alternative embodiments, the apparatus comprises acontainer designed to accommodate multiple buffer cores. In further oralternative embodiments, the apparatus comprises fewer than the maximumnumber of buffer cores the container is designed to accommodate. Infurther or alternative embodiments, the buffer displacement dam occupiesa position of the container which is designed to hold a buffer core. Infurther or alternative embodiments, the buffer displacement dam occupiesspace designed to hold a buffer core and space in the container designedto hold lower reservoir buffer. In further or alternative embodiments,the container is designed to hold two or more buffer cores, and thecontainer includes at least one buffer core, at least one gel cassette,and a buffer displacement dam.

In further or alternative embodiments, the buffer displacement dam usedin an gel electrophoresis apparatus has at least four walls that definean interior space, and the dimensions of the buffer displacement damconforms to the inner dimension of one end of the container of such anapparatus. In further or alternative embodiments, the bufferdisplacement dam includes a wall that can be engaged by a cam lockdevice for sealing at least one gel cassette to a buffer core in such anapparatus. In further or alternative embodiments, the cam lock device isan expanding cam lock device.

In further or alternative embodiments, in a gel electrophoresisapparatus the buffer displacement dam replaces a volume of from about 50milliliters to about 1,500 milliliters. In further or alternativeembodiments, in a gel electrophoresis apparatus the buffer displacementdam replaces a volume of from about 100 milliliters to about 1,500milliliters. In further or alternative embodiments, in a gelelectrophoresis apparatus the buffer displacement dam replaces a volumeof from about 200 milliliters to about 1,500 milliliters. In further oralternative embodiments, in a gel electrophoresis apparatus the bufferdisplacement dam replaces a volume of from about 400 milliliters toabout 1,000 milliliters. In further or alternative embodiments, in a gelelectrophoresis apparatus the buffer displacement dam replaces a volumeof from about 500 milliliters to about 750 milliliters.

In further or alternative embodiments, the gel electrophoresis apparatusis a midi gel apparatus and the buffer displacement dam replaces avolume of from about 50 milliliters to about 1,500 milliliters. Infurther or alternative embodiments, the gel electrophoresis apparatus isa midi gel apparatus and the buffer displacement dam replaces a volumeof from about 100 milliliters to about 1,500 milliliters. In further oralternative embodiments, the gel electrophoresis apparatus is a midi gelapparatus and the buffer displacement dam replaces a volume of fromabout 200 milliliters to about 1,500 milliliters. In further oralternative embodiments, the gel electrophoresis apparatus is a midi gelapparatus and the buffer displacement dam replaces a volume of fromabout 400 milliliters to about 1,000 milliliters. In further oralternative embodiments, the gel electrophoresis apparatus is a midi gelapparatus and the buffer displacement dam replaces a volume of fromabout 500 milliliters to about 750 milliliters.

In further or alternative embodiments, the gel electrophoresis apparatusis an electrophoretic transfer apparatus and the buffer displacement damreplaces a volume of from about 50 milliliters to about 1,500milliliters. In further or alternative embodiments, the gelelectrophoresis apparatus is an electrophoretic transfer apparatus andthe buffer displacement dam replaces a volume of from about 100milliliters to about 1,500 milliliters. In further or alternativeembodiments, the gel electrophoresis apparatus is an electrophoretictransfer apparatus and the buffer displacement dam replaces a volume offrom about 200 milliliters to about 1,500 milliliters. In further oralternative embodiments, the gel electrophoresis apparatus is anelectrophoretic transfer apparatus and the buffer displacement damreplaces a volume of from about 400 milliliters to about 1,000milliliters. In further or alternative embodiments, the gelelectrophoresis apparatus is an electrophoretic transfer apparatus andthe buffer displacement dam replaces a volume of from about 500milliliters to about 750 milliliters.

In further or alternative embodiments, the buffer displacement dam maybe used for replacing transfer buffer in an electrophoretic transferapparatus, in which the buffer displacement dam includes a bottom and atleast four walls that define an interior space, and the four wallsbuffer displacement dam conform to the internal dimensions of at least aportion of the container of the electrophoretic transfer apparatus. Infurther or alternative embodiments, the buffer displacement dam may beused for replacing electrophoresis buffer in a gel electrophoresisapparatus, in which the buffer displacement dam includes a bottom and atleast four walls that define an interior space, and the four wallsbuffer displacement dam conform to the internal dimensions of at least aportion of a buffer reservoir of the electrophoretic transfer apparatus.In further or alternative embodiments, the buffer displacement dam ofsuch an electrophoresis apparatus includes a buffer tank that canaccommodate multiple buffer cores, and the buffer displacement damconforms to the internal dimensions of the buffer tank, and the bufferdisplacement dam is designed to occupy the position of at least one ofthe multiple buffer cores when positioned in the buffer tank. In furtheror alternative embodiments, the buffer displacement dam, when positionedin the buffer tank, occupies the space in the buffer tank that isdesigned to hold the second buffer core and space in the buffer tankthat holds buffer during use of the apparatus in the absence of thebuffer displacement dam.

In further or alternative embodiments, the buffer displacement dam canfit into a midi-gel apparatus container. In further or alternativeembodiments, the buffer displacement dam is from about 3 to about 30inches in height. In further or alternative embodiments, the bufferdisplacement dam is from about 3 to about 20 inches in height. Infurther or alternative embodiments, the buffer displacement dam is fromabout 3 to about 10 inches in height. In further or alternativeembodiments, the buffer displacement dam is from about 3 to about 6inches in height. In further or alternative embodiments, the bufferdisplacement is from about 3.5 to about 5 inches in height. In furtheror alternative embodiments, the buffer displacement dam is about 4.5inches in height. In further or alternative embodiments, the bufferdisplacement dam is from about 4 to about 40 inches in length. Infurther or alternative embodiments, the buffer displacement dam is fromabout 4 to about 30 inches in length. In further or alternativeembodiments, the buffer displacement dam is from about 4 to about 20inches in length. In further or alternative embodiments, the bufferdisplacement dam is from about 4 to about 10 inches in length. Infurther or alternative embodiments, the buffer displacement dam is fromabout 4 to about 8 inches in length. In further or alternativeembodiments, the buffer displacement dam is about 6.14 inches in length.In further or alternative embodiments, the buffer displacement dam isfrom about 1 to about 25 inches in width. In further or alternativeembodiments, the buffer displacement dam is from about 1 to about 20inches in width. In further or alternative embodiments, the bufferdisplacement dam is from about 1 to about 15 inches in width. In furtheror alternative embodiments, the buffer displacement dam is from about 1to about 10 inches in width. In further or alternative embodiments, thebuffer displacement dam is from about 1 to about 5 inches in width. Infurther or alternative embodiments, the buffer displacement dam is fromabout 1 to about 3 inches in width. In further or alternativeembodiments, the buffer displacement dam is about 1.66 inches in width.In further or alternative embodiments, the buffer displacement dam has alip on one end.

In another aspect described herein are methods for performingelectrophoretic transfer of one or more biomolecules from a gel to afilter or membrane, wherein such methods include positioning within abuffer tank a gel cassette comprising a transfer membrane and a gel thatcomprises one or more biomolecules, wherein the buffer tank comprises orcontacts two electrodes; adding a buffer displacement dam to the buffertank; adding transfer buffer to the buffer tank; connecting a powersource to the two electrodes; and applying a voltage across the gel tocause electrophoretic transfer of the one or more biomolecules from thegel to the transfer membrane.

In another aspect described herein are methods for performingelectrophoretic separation of one or more biomolecules, wherein suchmethods include positioning at least one gel cassette in a gelelectrophoresis apparatus such that one end of a gel enclosed within thegel cassette is in contact with a first buffer reservoir and another endof the gel enclosed within the gel cassette is in contact with a secondbuffer reservoir, wherein the first buffer reservoir comprises orcontacts a first electrode and the second buffer reservoir comprises orcontacts a second electrode; adding a buffer displacement dam to the fgel electrophoresis apparatus; adding electrophoresis buffer to thefirst buffer reservoir and the second reservoir; adding one or moresamples comprising one or more biomolecules to sample wells at one endof the gel; connecting the first electrode and the second electrode to apower source; and applying a voltage across the gel to separate one ormore biomolecules.

In another aspect described herein is a buffer displacement dam forreplacing electrophoresis buffer in an electrophoretic apparatus havinga tank, an anode reservoir, and a cathode reservoir, wherein the bufferdam comprises non-conductive material and is positioned within a tank ofthe biological research apparatus in a position otherwise occupied by abuffer core, such that less than 90% of the buffer is necessary withineither the anode reservoir or the cathode reservoir compared to theamount of buffer required in the absence of the buffer displacement dam.In further or alternative embodiments, the electrophoretic apparatus isa gel electrophoresis apparatus. In further or alternative embodiments,the electrophoretic is a gel blotting apparatus. In further oralternative embodiments, wherein less than 75% of the buffer is requiredthan is necessary in the absence of the buffer displacement dam. Infurther or alternative embodiments, wherein less than 50% of the bufferis required than is necessary in the absence of the buffer displacementdam. In further or alternative embodiments, wherein less than 25% of thebuffer is required than is necessary in the absence of the bufferdisplacement dam. In further or alternative embodiments, wherein lessthan 5% of the buffer is required than is necessary in the absence ofthe buffer displacement dam.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention may be derived byreferring to the detailed description and claims when considered inconjunction with the following figures, wherein like reference numbersrefer to similar elements throughout the figures.

FIG. 1 is an exploded perspective view of an electrophoresis cellassembly that includes an expanding cam lock configured in accordancewith an example embodiment of the invention.

FIG. 2 is an exploded perspective view of the expanding cam lock shownin FIG. 1.

FIG. 3 is a vertical sectional view of an assembled expanding cam lockin the retracted position.

FIG. 4 is a vertical sectional view of an assembled expanding cam lockin the expanded position.

FIG. 5 is a phantom side view of an electrophoresis cell assembly thatincludes an expanding cant lock in the retracted position.

FIG. 6 is a phantom side view of an electrophoresis cell assembly thatincludes an expanding cam lock in the expanded position.

FIG. 7 is a depiction of a gel electrophoresis apparatus that includes abuffer displacement dam.

FIG. 8 shows two views of one example of a buffer displacement dam ofthe present invention. A) perspective view B) side cross-sectional view.

DETAILED DESCRIPTION

Unless otherwise defined, all technical and scientific terms used hereinhave the meaning commonly understood by one skilled in the biotechnologyart. All publications, patent applications, patents, and otherreferences mentioned herein are incorporated by reference in theirentirety. In case of conflict, the present specification, includingdefinitions, will control.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription. The following detailed descriptions are merely illustrativein nature and is not intended to limit the invention or the applicationand uses of the invention. Furthermore, there is no intention to bebound by any expressed or implied theory presented in the precedingtechnical field, background, brief summary or the following detaileddescriptions.

Expanding Cam Lock

The expanding cam lock described herein may be used in variouselectrophoresis apparatuses, including but not limited to gelelectrophoresis apparatuses, to secure and/or seal at least oneelectrophoresis gel cassette within the electrophoresis apparatus. Theexpanding cam lock comprises i) a base plate having a first surfaceadapted to engage either a partition assembly or a buffer core assemblywhich includes at least one electrophoresis gel cassette; ii) a followerplate having a second surface adapted to engage either a partitionassembly or a buffer core assembly which includes at least oneelectrophoresis gel cassette; and iii) a cam positioned between andmoveably coupled with the base plate and the follower plate. The baseplate and the follower plate are slideably coupled together andconfigured for insertion between the buffer core assemblies or thepartition assembly and buffer core assembly in the electrophoresisapparatus. The cam may also be pivotally coupled to the base plate andmay be configured to slideably engage the follower plate. The cam ismovable from a first position to a second position which urges orotherwise moves the base plate and the follower plate toward either abuffer core assembly or a partition assembly, depending on theconfiguration used with the expanding cam lock. The first surface of thebase plate and the second surface of the follower plate will contacteither an electrophoresis gel cassette of a buffer core assembly or apartition assembly, and thereby sealing the electrophoresis gel cassetteto the buffer core assembly. By way of example only, the followingconfigurations may be used,

1) the base plate may move toward and the first surface of the baseplate may contact an electrophoresis gel cassette of a buffer coreassembly, while the follower plate may move toward and the secondsurface of the follower plate may contact a partition assembly;

ii) the base plate may move toward and the first surface of the baseplate may contact a partition assembly, while the follower plate maymove toward and the second surface of the follower plate may contact anelectrophoresis gel cassette of a buffer core assembly;

iii) the base plate may move toward and the first surface of the baseplate may contact an electrophoresis gel cassette of a buffer coreassembly, while the follower plate may move toward and the secondsurface of the follower plate may contact a different electrophoresisgel cassette of a different buffer core assembly; or

iv) the base plate may move toward and the first surface of the baseplate may contact a partition assembly, while the follower plate maymove toward and the second surface of the follower plate may contact apartition assembly.

The electrophoresis apparatus, in which the expanding cam lock is used,includes a container wherein the expanding cam lock, buffer coreassembly or buffer core assemblies, electrophoresis gel cassette(s), andpartition assembly are placed. The partition assembly is either a buffercore assembly comprising at least one electrophoresis gel cassette, orthe partition assembly is an object which may be used to partition orblock out the electrophoresis container into smaller volume increments.Such objects include, but are not limited to, a buffer dam and a bufferdisplacement dam.

As used herein a buffer dam is a barrier which blocks the access ofbuffer from one region of the container into another region of thecontainer, thereby partitioning the container. By way of example only,such a buffer dam may resemble a buffer core wherein a wall is presentinstead of a gel cassette. Alternatively, such a buffer dam may be asimple wall, plate, wedge, or shim which is inserted into the containerand becomes a barrier to block buffer flow or redistribution.

As used herein a buffer displacement dam is a barrier which blocks theaccess of buffer from one region of the container into another region ofthe container, thereby partitioning the container. A buffer displacementdam is an object which is placed into an electrophoresis container andoccupies the space in the container which would otherwise be taken up bybuffer. A buffer displacement dam serves to occupy the space which wouldotherwise be occupied by buffer, while a buffer dam blocks the bufferfrom moving into empty regions.

The expanding cam lock described herein may be used in anelectrophoresis apparatus to secure and/or seal multiple buffer coresand each buffer core may include multiple electrophoresis gel cassettes.By way of example only, the expanding cam lock may be used to secureand/or seal 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,18, 19, 20, 21, 22, 23, or 24 buffer cores with 1, 2, 3, 4, 5, 6, 7, 8,9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24 gelcassettes per buffer core. In addition, multiple expanding cams may beused per electrophoresis apparatus. By way of example only, the numberof expanding cam locks which may be used in an electrophoresis apparatusmay be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,19, 20, 21, 22, 23, or 24.

An exploded perspective view of an electrophoresis system 10 includingan exemplary embodiment of the present invention is shown in FIG. 1. Thesystem 10 includes a container 12, a lid 20, an expanding cam lock 22,and first and second buffer core assemblies 24. Each buffer coreassembly 24 includes a buffer core body 14 and gel cassettes 16 and 18.

Container 12 includes side walls 26 and 28, end walls 30 and 32, and aclosed bottom 34. Container 12 is open at the top for receiving a firstelectrophoresis buffer solution (not shown). Located on opposite innersurfaces of side walls 26 and 28 and spaced away from the end walls 30and 32 of container 12 are wall recesses 44 and 46. Wall recesses 44 and46 are aligned with each other to receive each buffer core assembly 24and are integrally formed with side walls 26 and 28, respectively. Eachof the wall recesses 44 and 46 has a cross-section resembling anirregular C-channel when viewed from the top of container 12.

Wall recesses 44 and 46 are sized to accommodate the lateral width 53 ofbuffer core assembly 24 without significant lateral movement. The widthof wall recesses 44 and 46 is slightly greater than width 53 tofacilitate the placement of each buffer core assembly 24 in container12.

Container 12 also features vertical ridges 48 and 50. Vertical ridges 48and 50 extend along the height of container 12 where wall recesses 44and 46 open to side walls 26 and 28 toward end walls 30 and 32 ofcontainer 12. Vertical ridges 48 and 50 abut each buffer core assembly24 in its installed position, as will be discussed in further detailbelow.

Each buffer core assembly 24 includes gel cassettes 16 and 18, which areplaced on a front side 54 and a back side 56 of buffer core body 14 toform a portion of the sides of an upper buffer chamber 52. Upper bufferchamber 52 is liquid-tight and holds a second electrically chargeablebuffer solution. In practice, upper buffer chamber 52 often is referredto as the anode chamber or the cathode chamber, depending on thepolarity of the applied voltage or applied current to the buffersolution contained in upper buffer chamber 52.

Buffer core body 14 is generally U-shaped, and includes spaced-apartupraised side members 58 and 60, a base 62 and a beam 64. Beam 64provides support for and connects side members 58 and 60, and ispositioned approximately halfway between the front and back sides ofbuffer core body 14. Flanges 66 and 68 are located at the top portionsof side members 58 and 60, respectively.

Gel cassettes 16 and 18 are positioned on each of the front side 54 andback side 56 of buffer core body 14 in a sandwiched fashion. Gelcassettes 16 and 18 have a front surface 80 and a back surface 82. Eachgel cassette includes a pair of thin wall plates that are commonlyreferred to as the divider or divider plate 84 and the retainer orretainer plate 86. Retainer plate 86 is slightly shorter in height thandivider plate 84.

Divider plate 84 is affixed to a peripheral ridge (not shown) along thelateral sides and the bottom periphery of retainer plate 86 to define aninternal gel compartment 88 for holding an electrophoresis gel (notshown). Gel compartment 88 has a comb opening 90 at the top portion ofthe cassette for receiving a sample that is to be electrophoreticallyseparated. Located along the lower portion of divider plate 84 andtraversing the width of each of gel cassettes 16 and 18 is an opening 92that opens gel compartment 88 to the exterior of the cassette.

Various electrophoresis gel cassettes, also herein referred to gelcassettes, may be used in conjunction with the expanding cam lockdescribed herein. By way of example only, in typical applications, thegel cassette has a height and width between 4 inches (10 cm) and 8inches (20 cm). Although gel cassettes are available in various shapes,sizes, and widths (such as mini-gel cassettes, wide-format gelcassettes, or full size gel cassettes), the invention is not limited toany specific size of gel cassette. In addition, by way of example only,a gel cassette may have the gel pre-filled within the internal gelcompartment for ease of handling. The comb opening 90 is closed with acomb (not shown) and opening 92 is masked closed with a removable tape(not shown). An example of the gel cassettes which may be used inconjunction with the expanding cam lock described herein are theTris-glycine gels sold by Invitrogen Corporation, of San Diego, Calif.,Catalog No. EC6005. Gel cassettes of similar types are also commerciallyavailable from other sources.

Gel cassettes 16 and 18 are positioned adjacent each of front side 54and back side 56 of buffer core body 14 in a sandwiched fashion todefine upper buffer chamber 52 for receiving the second buffer solution(not shown). As will be described in more detail below, the secondbuffer solution is isolated from the first buffer solution in container12. In view of the isolation of the two buffer solutions, the portion ofcontainer 12 that contains the first buffer solution is often referredto as the lower buffer chamber, as distinguished from upper bufferchamber 52.

Both the front and rear surfaces of buffer core body 14 are providedwith grooves 94 and 96 for fining and holding resilient strips 98 and100, respectively, as a seal between gel cassettes 16 and 18 and buffercore body 14. The seal ensures isolation of the second buffer solutionin upper buffer chamber 52 from the first buffer solution in container12, and provides a cushion to reduce excess stress along the forcebearing surfaces of the cassettes when they are held against buffer corebody 14.

Prior to using gel cassettes 16 and 18, the comb (not shown) and thetape (not shown) are removed. The sample to be analyzed is introducedinto gel compartment 88 through comb opening 90 by appropriate means,such as a pipette. Each buffer core assembly 24 is then slidablyinserted into wall recesses 44 and 46 from the top of the container 12to rest on risers 104 (see FIG. 5) inside container 12. Risers 104elevate buffer core assemblies 24 to permit the first buffer solution topass below and surround the front and back sides of buffer coreassemblies 24. Buffer core assemblies 24 are positioned toward end walls30 and 32 of container 12 such that side ridges 102 of gel cassette 18are aligned coincidentally with and bear upon vertical ridges 48 and 50.

Although the above description refers to the use of two gel cassettes aspart of each buffer core assembly 24, the present invention may also beused with more or less than two cassettes in each buffer core assembly24. For example, a single cassette can be installed on one side ofbuffer core body 14, and a blank or a plate member can be placed on theother side to achieve similar performance and results with assuredconsistency and uniformity.

FIG. 2 is an exploded perspective view of expanding cam lock 22, whichis used to secure buffer core assemblies 24 in container 12. Expandingcam lock 22 comprises three basic parts: a base plate 106; a followerplate 107; and cam 128.

Base plate 106 includes a generally square or rectangular front panel108 and contact surfaces 110 and 112 on the lateral sides of front panel108. At the lower portion of base 114 of front panel 108, a plurality ofupraised push tabs 115 are provided to bear upon the bottom edge ofdivider plate 84 (shown in FIG. 1). Affixed to the reverse side of frontpanel 108, a pair of spaced apart parallel side panels 116 and 118 isprovided to enhance structural integrity of base plate 106 and to couplewith side panels 117 and 119 on follower plate 107. Side panels 116 and118 substantially align with contact surfaces 110 and 112, respectivelyand include axle bushings 120 and 122. Each side panel 116 and 118 mayinclude one or more slots 170 for coupling with follower plate 107 andfront panel 108 may include one or more through holes 172 adjacent theslots.

Follower plate 107 is generally similar to base plate 106 and includes agenerally square or rectangular front panel 109 and contact surfaces 111and 113. At a lower portion of base of front panel 109, a plurality ofupraised push tabs are provided (not shown but similar to push tabs 115)to bear upon the bottom edge of divider plate 84. Affixed to the reverseside of front panel 109, a pair of spaced apart parallel side panels 117and 119 is provided to enhance structural integrity of follower plate107. Side panels 117 and 119 substantially align with contact surfaces111 and 115, respectively. Bases 124 and 126 of side panels 117 and 119extend from the back surface 142 of front panel 108. An inner surface174 of side panels 117 and 119 is configured to slide against an outersurface 176 of side panels 116 and 118 of the base plate 106. Sidepanels 117 and 119 also include one or more lever arms 176 with lockingends 178 (see FIG. 3). Slots 170 are configured and sized to acceptlever arms 176 and locking ends 178 to slideably couple the base plate106 and the follower plate 107. The locking ends 178 may also include anangled end portion to facilitate assembly.

Cam 128 includes cam arms 130 and 132, a push bar 134, a grip or handle138 and axle pins 140 and 141. Axle pins 140 and 141 extend through andfreely pivot in axle bushings 120 and 122 of side panels 116 and 118. Asshown in FIG. 3, push bar 134 extends between cam arms 130 and 132 andincludes plates 136 and 137, and curved end 148. Referring again to FIG.2, grip 138 is used to pivot cam 128 relative to base plate 106 andfollower plate 107. A recess or opening 190 in cam 128 providesclearance for a top portion 188 of front panel 108 when expanding camlock 22 is in the expanded position (shown in FIG. 4). The length ofhandle 138 is longer than push bar 134, hence the force that is appliedto handle 138 is multiplied by the ratio of lengths of handle 138 andpush bar 134. The mechanical advantage results in the force applied bypush bar 134 being greater than the force applied by the user to handle138. This allows higher sealing forces to be applied by the user.

The expanding cam lock described herein, including base plate 106,follower plate 107 and cam 128, may be fabricated from a number ofmaterials including, but not limited to polymeric materials. Suchpolymers include, but not limited to, styrene acrylonitrile (SAN),polyurethane, polyvinylchloride (PVC), polycarbonate, polystyrene (PS),acrylic-based polymers, nylon based polymers, polymethylmethacrylate(PMMA), polyethylene terephthalate (PET), glycol-modified polyethyleneterephthalate (PETG), polypropylene (PP), cyclo-olefin polymer (COP),polyphenylene ether (PPE), polyoxymethylene (POM), and copolymersthereof. Other representative materials that can be used to fabricatethe expanding cam lock described herein include, but are not limited toepoxy based polymers, cyclo-olefin copolymer (COC),polychlorotrifluoroethylene (PCTFE), polyetheretherketone (PEEK),polyetherimide (PEI), polyethersulfone (PES), polyethylene (PE), highdensity polyethylene (HDPE), low density polyethylene (LDPE),polyethylene naphthalate (PEN), polyester, polyhydroxybutyrate (PHB),polyhydroxyvalerate copolymer, polyimide (PI), polyoxymethylenecopolymer (POMC), polyoxymethylene copolymer (POMC), polyoxymethylenehomopolymer (POMH), polyphenyleneoxide (PPO), polyphenylenesulfide(PPS), polyphenylsulfone (PPSu), polystyrol, polysulphone (PSu),polytetrafluoroethylene (PTFE), polyvinyl fluoride (PVF),polyvinylidenechloride (PVDC), polybutyleneterephthalate (PBT),fluorinated ethylenepropylene (FEP), perfluoralkoxyalkane (PFA), andpolyvinylidenefluoride (PVDF).

The expanding cam Pock described herein, including base plate 106,follower plate 107 and cam 128, can be fabricated using a variety oftechniques, processes and methods. Such techniques, processes andmethods include, but are not limited to, molding techniques, hotembossing methods, casting processes, thermoforming methods,stereolithography processes, machining methods and milling processes.Such molding techniques include, but are not limited to, injectionmolded and compression molding. In the embodiments described herein, andby way of example only, The expanding cam lock described herein,including base plate 106, follower plate 107 and cam 128, may be formedby injection molding a plastic material, such as SAN (styreneacrylonitrile), Polycarbonate, Polystyrene, Acrylic, PMMA (polymethylmethacrylate), PET, PETG, or Polypropylene. Alternatively, the expandingcam lock described herein, including base plate 106, follower plate 107and cam 128, may be machined from polyoxymethylene copolymer, such asAcetel, or formed from high strength epoxies using a stereolithograpyprocesses.

Expanding cam lock 22 is assembled by first positioning cam 128 withinside panels 116 and 118 of base plate 106 and inserting axle pins 140and 141 into axle bushings 120 and 122. Axle pins 140 and 141 and/oraxle bushings 120 and 122 should have enough flexibility to allowflexing, entry and retention of axle pins 140 and 141 in axle bushings120 and 122. Follower plate 107 is then positioned such that innersurface 174 of side panels 117 and 119 engages outer surface 176 of sidepanels 116 and 118 of base plate 106. The angled ends of locking ends178 flex lever arms 176 until locking ends 178 slide along side panels116 and 118 and drop into slots 170, slideably locking base plate 106and follower 107 plate together with cam 128 sandwiched between.Follower plate 107 may be removed by flexing lever arms 176 untillocking ends 178 are out of slots 170 and then sliding follower plate107 away from base plate 106.

When assembled, cam 128 rotates around the X-axis through axle pins 140and 141. In the preferred embodiment, cam 128 cannot translate relativeto base plate 106 in the X, Y or Z directions, and base plate 106 andfollower plate 107 are slideably locked together such that they cannotrotate relative to each other. Slots 170 are elongated to allow lockingends 178 of lever arms 176 to move within slots 170 and allow base plate106 and follower plate 107 to translate (slide) along the Z direction.

FIGS. 3 and 4 are vertical cross-sectional views showing cam 128 in theopen position (FIG. 3) and the closed position (FIG. 4). As a force F,150 is applied to handle 138, cam 128 rotates around it's axle pins 140and 141. During rotation, push bar 134 rotates upward and begins to pushfollower plate 107 out of its path of rotation. This continues untilcurved end 148 of push bar 134 passes the orthogonal (90 degree) pointat which point it becomes “over-center”. The invention makes use of thisover-center attribute by stopping the rotation just a few degrees past90 degrees. In this position, cam 128 exerts outward forces on baseplate 106 and follower plate 107, which in turn exerts forces on theseals and cassettes to keep them in place within the container. Notethat cam 128 is prevented from over-rotating by the hard stops. Hence,it is compelled to stay in this expanded position until the user appliesan opposite force F₂ 152 to handle 138 which is greater and overridesthe inherent locking force.

FIG. 5 is a phantom side view that illustrates expanding cam lock 22inserted into container 12 with cam 128 disposed in an open positionwith handle 138 toward the right of container 12. On insertion, baseplate 106 is disposed adjacent gel cassette 16 of a first buffer coreassembly 24 and follower plate 107 is disposed adjacent a gel cassette16 of a second buffer core assembly 24. Expanding cam lock 22 includes acentral opening in the bottom portion to allow expanding cam lock 22 tostraddle a protrusion 180 on the bottom of container 12. As shown inFIG. 5, upon initial insertion into container 12, base plate 106 andfollower plate 107 are essentially parallel to each other and also togel cassettes 16.

FIG. 6 illustrates expanding cam lock 22 with cam 128 in a closedposition. In particular, cam 128 is shown rotated toward the left ofcontainer 12. As cam 128 is rotated left, curved end 148 bears againstwall 109 of the follower plate 107, causing the base plate 106 andfollower plate 107 to separate. As a result, contact surfaces 110 and112 of base plate 106 and contact surfaces 111 and 113 of follower plate107 align with and bear upon the gel cassettes 16, pressing gelcassettes 16 against buffer core bodies 14. Buffer core bodies 14 inturn bear upon gel cassettes 18, pressing gel cassettes 18 againstvertical ridges 48 (not shown) and 50. As cam 128 is further rotatedforward, curved end 148 passes through a plane extending perpendicularlyfrom wall 32 to the center of axle pins 140 and 141 (shown as dashedline 214 in FIGS. 4 and 6). Cam 128 therefore goes “over-center” at apoint where curved end 148 exceeds the point of maximum pressure againstfollower plate 107, thus locking the expanding cam lock 22 in position.Because force would be required to return cam 128 backward pastover-center (i.e., returning curved end 148 below dashed line 214), theover-center position of cam 128 secures base plate 106 and followerplate 107 against gel cassettes 16. Upon further forward motion of cam128, flat plate 136 of cam 128 contacts the back surface of front panel108, providing a positive stop that prevents cam 128 from furtherforward movement.

As contact surfaces 110 and 112 of base plate 106 and contact surfaces111 and 113 of follower plate 107 bear on side portions of gel cassettes16, a bearing force is transmitted through gel cassettes 16 and 18against resilient strips 100 and 98, respectively on each buffer corebody 14 to seal upper buffer chambers 52. This ensures fluid andelectrical isolation between the first and second buffer solutions incontainer 12 and in upper buffer chamber 52 to prevent mixing of the twobuffer solutions, which can interfere with proper molecular separation.It also reduces the risks of electrical grounding of the power supply orother sensitive instruments used in connection with the electrophoresis.The resiliency of the strips 98 and 100 also provides a means ofresistance against the bearing force of base plate 106 and followerplate 107 such that a static balance is maintained among buffer corebodies 14, gel cassettes 16 and 18, base plate 106, follower plate 107,cam 128 and end walls 30 and 32 of container 12, thereby securing themin container 12.

Cam 22 provides a consistent and reproducible clamping force on buffercore assemblies 24. In particular, because cam 128 is pivotally coupledto base plate 106, base plate 106 cannot slip relative to cam 128, andthereby inadvertently release pressure on buffer core assemblies 24.Further, once the curved end 148 goes “over center,” cam 22 is locked inposition and applies a consistent and reproducible clamping force tobuffer core assemblies 24 that does not depend upon the amount of forceapplied to handle 138.

During operation of the expanding cam described herein, the first andsecond buffer core assemblies 24 and expanding cam lock 22 are firstsecured within container 12 in the manner as described above. A firstbuffer solution is dispensed into each upper buffer chamber 52 abovecomb openings 90 of gel cassettes 16 and 18 to establish fluid contactwith the gel in the gel compartments. A second buffer solution is thenintroduced into container 12 until its level is approximately that ofbeam 64. Lid 20 is then positioned above the front portion of container12, the conductor cables 21 are attached to a power supply system orcharging means (not shown) and electrophoresis commences.

Electrophoreses Kit with an Expanding Cam Lock

The expanding cam lock described herein may be incorporated into anelectrophoresis kit. Such kits may include, among other components, anelectrophoresis container having a first end wall defining a firstrecess and a second end wall defining a second recess; at least onebuffer core assembly, a partition assembly, and an expanding cam lock.The expanding cam lock incorporated into such kits comprises a baseplate having a first surface adapted to engage a buffer core assemblyand having first side panels on the reverse side of the first surface; afollower plate having a second surface adapted to engage a partitionassembly and having second side panels on the reverse side of the secondsurface, the first and second side panels being slideably coupled andthe base plate and follower plate being configured for insertion betweenthe buffer core assembly and the partition assembly; and a cam pivotallycoupled to the base plate and the cam slidingly engaging the followerplate. The partition assembly of such kits, have been described herein,and include but are not limited, buffer dams, a buffer displacementdams, or buffer core assemblies comprising at least one electrophoresisgel cassette.

The cam of the expanding cam lock incorporated into an electrophoresiskit may also include axle pins which pivotally couple the cam to thebase plate. In addition, the cam may be movable from a first position toa second position which urges or otherwise moves the base plate and thefollower plate toward either a buffer core assembly or a partitionassembly, depending on the configuration used with the expanding camlock. The first surface of the base plate and the second surface of thefollower plate will contact either an electrophoresis gel cassette of abuffer core assembly or a partition assembly, and thereby sealing theelectrophoresis gel cassette to the buffer core assembly. By way ofexample only, the following configurations may be used,

i) the base plate may move toward and the first surface of the baseplate may contact an electrophoresis gel cassette of a buffer coreassembly, while the follower plate may move toward and the secondsurface of the follower plate may contact a partition assembly;

ii) the base plate may move toward and the first surface of the baseplate may contact a partition assembly, while the follower plate maymove toward and the second surface of the follower plate may contact anelectrophoresis gel cassette of a buffer core assembly;

iii) the base plate may move toward and the first surface of the baseplate may contact an electrophoresis gel cassette of a buffer coreassembly, while the follower plate may move toward and the secondsurface of the follower plate may contact a different electrophoresisgel cassette of a different buffer core assembly; or

iv) the base plate may move toward and the first surface of the baseplate may contact a partition assembly, while the follower plate maymove toward and the second surface of the follower plate may contact apartition assembly.

Additionally, the first surface of the base plate and second surface ofthe follower plate may include push tabs adapted to facilitate urging ofthe first surface and the second surface. Also, the first side panelsmay include slots and the second side panels may include lever arms withlocking portions configured to slideably engage the slots.

When the cam is in the second position, the cam may be configured tolock the base plate into engagement with either a partition assembly oran electrophoresis gel cassette of the buffer core and to lock thefollower plate into engagement with either a partition assembly or anelectrophoresis gel cassette of the buffer core.

The cam of the expanding cam lock incorporated into an electrophoresiskit may also include i) at least one push bar configured to engage thebase plate to prevent further urging of the first surface toward thebuffer core assembly and the second surface toward the partitionassembly; ii) at least one handle to pivot the cam relative to the baseplate and follower plate; and/or iii) a curved end that slidinglyengages the follower plate.

The components of such electrophoresis kits, including but not limitedto, the electrophoresis container, the base plate, the follower plate,the cam, the partition assembly or the buffer core assembly may be madeof various materials, such as polymers, metals, or combinations thereof.The polymer used may be selected from the group consisting of styreneacrylonitrile (SAN), polyurethane, polyvinylchloride (PVC),polycarbonate, polystyrene (PS), acrylic-based polymers, nylon basedpolymers, polymethylmethacrylate (PMMA), polyethylene terephthalate(PET), glycol-modified polyethylene terephthalate (PETG), polypropylene(PP), cyclo-olefin polymer (COP), polyphenylene ether (PPE),polyoxymethylene (POM), and copolymers thereof. Other representativematerials that can be used to fabricate these components include, butare not limited to epoxy based polymers, cyclo-olefin copolymer (COC),polychlorotrifluoroethylene (PCTFE), polyetheretherketone (PEEK),polyetherimide (PEI), polyethersulfone (PES), polyethylene (PE), highdensity polyethylene (HDPE), low density polyethylene (LDPE),polyethylene naphthalate (PEN), polyester, polyhydroxybutyrate (PHB),polyhydroxyvalerate copolymer, polyimide (PI), polyoxymethylenecopolymer (POMC), polyoxymethylene copolymer (POMC), polyoxymethylenehomopolymer (POMH), polyphenyleneoxide (PPO), polyphenylenesulfide(PPS), polyphenylsulfone (PPSu), polystyrol, polysulphone (PSu),polytetrafluoroethylene (PTFE), polyvinyl fluoride (PVF),polyvinylidenechloride (PVDC), polybutyleneterephthalate (PBT),fluorinated ethylenepropylene (FEP), perfluoralkoxyalkane (PFA), andpolyvinylidenefluoride (PVDF).

In addition, the components of such electrophoresis kits, including butnot limited to, the electrophoresis container, the base plate, thefollower plate, the cam, the partition assembly or the buffer coreassembly may be fabricated by molding techniques, hot embossing methods,casting processes, thermoforming methods, stereolithography processes,machining methods and milling processes. Such molding methods include,but are not limited to, injection molding and compression molding.

Electrophoresis Assembly with an Expanding Cam Lock

The expanding cant lock described herein may be incorporated into anelectrophoresis assembly for sealing at least one electrophoresis gelcassette to a buffer core assembly in the electrophoresis assembly. Thecomponents of such assemblies include, but are not limited to anelectrophoresis container having a first end wall defining a firstrecess and a second end wall defining a second recess; a buffer coreassembly with at least one gel cassette or a partition assembly disposedin the container proximate the first end wall; a different buffer coreassembly with at least one gel cassette or a different partitionassembly disposed in the container proximate the second end wall; and anexpanding cam lock for sealing at least one electrophoresis gel cassetteto a buffer core assembly.

The expanding cam lock of such electrophoresis assemblies include a baseplate having a first surface adapted to engage either a partitionassembly or a buffer core assembly with at least one gel cassette andthe base plate has first side panels on the reverse side of the firstsurface; a follower plate having a second surface adapted to engageeither a partition assembly a buffer core assembly with at least one gelcassette, and the follower plate has second side panels on the reverseside of the second surface, the first and second side panels areslideably coupled and the base plate and follower plate being configuredfor insertion between the buffer core assemblies, partition assembly orcombinations thereof; and a cam pivotally coupled to the base plate andthe cam slidingly engaging the follower plate to urge the second surfacetoward either a partition assembly or a buffer core assembly and to urgethe first surface either a different partition assembly or a differentbuffer core assembly, thereby securing and/or sealing one or moreelectrophoresis gel cassettes in the buffer core assemblies.

The partition assembly of such electrophoresis assemblies have beendescribed herein, and include but are not limited, buffer dams, a bufferdisplacement dams, or buffer core assemblies comprising at least oneelectrophoresis gel cassette.

The cam of the expanding cam lock incorporated into an electrophoresisassemblies may also include axle pins which pivotally couple the cam tothe base plate. In addition, the cam may be movable from a firstposition to a second position which urges or otherwise moves the baseplate and the follower plate toward either a buffer core assembly or apartition assembly, depending on the configuration used with theexpanding cam lock. The first surface of the base plate and the secondsurface of the follower plate will contact either an electrophoresis gelcassette of a buffer core assembly or a partition assembly, and therebysealing the electrophoresis gel cassette to the buffer core assembly. Byway of example only, the following configurations may be used,

i) the base plate may move toward and the first surface of the baseplate may contact an electrophoresis gel cassette of a buffer coreassembly, while the follower plate may move toward and the secondsurface of the follower plate may contact a partition assembly;

ii) the base plate may move toward and the first surface of the baseplate may contact a partition assembly, while the follower plate maymove toward and the second surface of the follower plate may contact anelectrophoresis gel cassette of a buffer core assembly;

iii) the base plate may move toward and the first surface of the baseplate may contact an electrophoresis gel cassette of a buffer coreassembly, while the follower plate may move toward and the secondsurface of the follower plate may contact a different electrophoresisgel cassette of a different buffer core assembly; or

iv) the base plate may move toward and the first surface of the baseplate may contact a partition assembly, while the follower plate maymove toward and the second surface of the follower plate may contact apartition assembly.

Additionally, the first surface of the base plate and second surface ofthe follower plate may include push tabs adapted to facilitate urging ofthe first surface and the second surface. Also, the first side panelsmay include slots and the second side panels may include lever arms withlocking portions configured to slideably engage the slots.

When the cam is in the second position, the cam may be configured tolock the base plate into engagement with either a partition assembly oran electrophoresis gel cassette of the buffer core and to lock thefollower plate into engagement with either a partition assembly or anelectrophoresis gel cassette of the buffer core.

The cam of the expanding cam lock incorporated into an electrophoresisassemblies may also include i) at least one push bar configured toengage the base plate to prevent further urging of the first surfacetoward the buffer core assembly and the second surface toward thepartition assembly; ii) at least one handle to pivot the cam relative tothe base plate and follower plate; and/or iii) a curved end thatslidingly engages the follower plate.

The components of such electrophoresis assemblies, including but notlimited to, the electrophoresis container, the base plate, the followerplate, the cam, the partition assembly or the buffer core assembly maybe made of various materials, such as polymers, metals, or combinationsthereof. The polymer used may be selected from the group consisting ofstyrene acrylonitrile (SAN), polyurethane, polyvinylchloride (PVC),polycarbonate, polystyrene (PS), acrylic-based polymers, nylon basedpolymers, polymethylmethacrylate (PMMA), polyethylene terephthalate(PET), glycol-modified polyethylene terephthalate (PETG), polypropylene(PP), cyclo-olefin polymer (COP), polyphenylene ether (PPE),polyoxymethylene (POM), and copolymers thereof. Other representativematerials that can be used to fabricate these components include, butare not limited to epoxy based polymers, cyclo-olefin copolymer (COC),polychlorotrifluoroethylene (PCTFE), polyetheretherketone (PEEK),polyetherimide (PEI), polyethersulfone (PES), polyethylene (PE), highdensity polyethylene (HDPE), low density polyethylene (LDPE),polyethylene naphthalate (PEN), polyester, polyhydroxybutyrate (PHB),polyhydroxyvalerate copolymer, polyimide (PI), polyoxymethylenecopolymer (POMC), polyoxymethylene copolymer (POMC), polyoxymethylenehomopolymer (POMH), polyphenyleneoxide (PPO), polyphenylenesulfide(PPS), polyphenylsulfone (PPSu), polystyrol, polysulphone (PSu),polytetrafluoroethylene (PTFE), polyvinyl fluoride (PVF),polyvinylidenechloride (PVDC), polybutyleneterephthalate (PBT),fluorinated ethylenepropylene (FEP), perfluoralkoxyalkane (PFA), andpolyvinylidenefluoride (PVDF).

In addition, the components of such electrophoresis assemblies,including but not limited to, the electrophoresis container, the baseplate, the follower plate, the cam, the partition assembly or the buffercore assembly may be fabricated by molding techniques, hot embossingmethods, casting processes, thermoforming methods, stereolithographyprocesses, machining methods and milling processes. Such molding methodsinclude, but are not limited to, injection molding and compressionmolding.

Buffer Displacement Dam

In another aspect of the invention, a buffer displacement dam isprovided that fits inside a gel electrophoresis apparatus orelectrophoretic gel transfer apparatus buffer reservoir and occupiesspace that, during the use of the apparatus, would otherwise be taken upby buffer. A gel electrophoresis apparatus or electrophoretic transferapparatus that includes a buffer displacement dam therefore uses lessbuffer than it would use without a buffer displacement dam. For example,when inserted into a buffer reservoir, a buffer displacement dam candisplace 10% or more of buffer that would otherwise be used in anelectrophoresis apparatus or electrophoretic transfer apparatus duringelectrophoresis or electroblotting. Preferably, a buffer displacementdam replaces 20% or more of buffer that would otherwise be used in anelectrophoresis apparatus or electrophoretic transfer apparatus, morepreferably 30% or more, and more preferably yet 40% or more of bufferthat would otherwise be used in an electrophoresis apparatus orelectrophoretic transfer apparatus.

A buffer displacement dam used to displace electrophoresis buffer ortransfer buffer fits into a buffer reservoir such that it conforms insize to the reservoir in at least one dimension. In other words, atleast one side or wall of a buffer displacement dam spans the width orlength of a buffer reservoir or aligns along at least one wall or sideof a buffer reservoir when the displacement dam is inserted into thebuffer reservoir. Preferably, a buffer displacement dam has the samedepth as the buffer reservoir it inserts into, but this is notnecessarily the case. Preferably a buffer displacement dam according tothe present invention fits into the tank such that it stays in a fixedposition within the tank. For example, the displacement dam can slideinto the tank and be fixed in position by means of grooves, ridges,flanged edges along the top of the sides of the displacement dam, oreven clips, cam locks or other fasteners. In a preferred embodiment,however, a buffer displacement dam conforms to the inner dimensions ofat least a portion of a buffer tank such that it can be slid into thebuffer tank where it fits snugly without requiring additional structuresfor attachment. For example, a buffer displacement dam can havedimensions such that it fits one end of a buffer reservoir by conformingto the interior of a curved wall of the buffer reservoir or to theinterior of two or more non-curved walls of the buffer reservoir suchthat it fits within the buffer reservoir to remain in a fixed positionwithin the tank. A buffer displacement dam is preferably of the sameheight as the buffer reservoir it fits into, although this is not arequirement of the present invention. The buffer tank can optionallyhave a lip or handle that extends beyond the outer edge of one or moreareas of the buffer reservoir it fits into that can facilitate insertionand removal of the buffer displacement dam.

In some preferred embodiments, a buffer displacement dam has at leastfour sides and conforms to the dimensions of a buffer reservoir in thatat least three of the sides align along the interior of sides of thebuffer reservoir such that the buffer displacement dam fits one end of abuffer reservoir, such that when the buffer displacement dam ispositioned in the buffer reservoir, the buffer dam fills space thatwould otherwise be taken up by buffer during the use of the gelelectrophoresis or electrophoretic transfer apparatus. For example, FIG.7 depicts a buffer displacement dam having four sides, in which three ofthe sides align along the interior of one end of a buffer reservoir.Although not visible in the figure, the bottom of the displacement damshown aligns along the bottom of the buffer reservoir (gel systemcontainer).

Although a buffer displacement dam conforms to the interior dimensionsof at least a portion of a buffer reservoir, it need not conformprecisely. For example, it may not have a shape that fits into groovesor minor indentations of a buffer reservoir. Essentially, a displacementdam should conform to the interior dimensions of at least a portion of abuffer reservoir such that it fits the buffer reservoir sufficientlyclosely that it stays in position without bobbing or sliding out ofposition in the tank, but not so tightly that it is difficult to insertand remove.

A buffer displacement dam can be solid but is preferably at leastpartially hollow, making the buffer displacer lighter and less expensiveto manufacture than a solid piece. For example, a buffer displacementdam can comprise a bottom and a curved circumference or curved ornoncurved sides, in which the circumference or sides of the bufferdisplacement dam conforms to the inner dimensions of at least a portionof a buffer reservoir, and the circumference or sides are in the form ofa wall or walls that define an interior space. The sides or walls can bestraight or curved, and regular or irregular in shape. A bufferdisplacement dam can have a single wall that is curved to circumscribe acircular, ovoid, or other regular or irregular curved shape. Thedisplacement dam can have one or more internal walls or supportstructures far structural support. The buffer displacement dam ispreferably open at the top, although this is not a requirement of theinvention.

The buffer displacement dam may be fabricated from materials which arefluid-impermeable and non-conducting. By way of example only, suchsuitable materials, include polymeric materials, may be fabricated fromvarious polymeric materials. Such polymers include, but not limited to,styrene acrylonitrile (SAN), polyurethane, polyvinylchloride (PVC),polycarbonate, polystyrene (PS), acrylic-based polymers, nylon basedpolymers, polymethylmethacrylate (PMMA), polyethylene terephthalate(PET), glycol-modified polyethylene terephthalate (PETG), polypropylene(PP), cyclo-olefin polymer (COP), polyphenylene ether (PPE),polyoxymethylene (POM), and copolymers thereof. Other representativematerials that can be used to fabricate the gel cassette adaptor 30include, but are not limited to epoxy based polymers, cyclo-olefincopolymer (COC), polychlorotrifluoroethylene (PCTFE),polyetheretherketone (PEEK), polyetherimide (PEI), polyethersulfone(PES), polyethylene (PE), high density polyethylene (HDPE), low densitypolyethylene (LDPE), polyethylene naphthalate (PEN), polyester,polyhydroxybutyrate (PHB), polyhydroxyvalerate copolymer, polyimide(PI), polyoxymethylene copolymer (POMC), polyoxymethylene copolymer(POMC), polyoxymethylene homopolymer (POMH), polyphenyleneoxide (PPO),polyphenylenesulfide (PPS), polyphenylsulfone (PPSu), polystyrol,polysulphone (PSu), polytetrafluoroethylene (PTFE), polyvinyl fluoride(PVF), polyvinylidenechloride (PVDC), polybutyleneterephthalate (PBT),fluorinated ethylenepropylene (FEP), perfluoralkoxyalkane (PFA), andpolyvinylidenefluoride (PVDF).

In addition, the buffer displacement dam may be fabricated using moldingtechniques, hot embossing methods, casting processes, thermoformingmethods, stereolithography processes, machining methods and millingprocesses. Such molding techniques include, but are not limited to,injection molded and compression molding.

A displacement dam can be used, for example, in a “wet” electroblottingapparatus to occupy space in the buffer reservoir that would otherwisebe taken up by transfer buffer. A displacement dam designed for use inan electroblotter is designed to fit into a buffer reservoir (buffertank) that holds one or more gel cassettes, such that its position doesnot interfere with the passage of electrical current through the one ormore gel cassettes inserted in the electroblotting device.

In one example, an electrophoretic transfer apparatus that is designedfor transferring biomolecules (such as but not limited to proteins ornucleic acids) from a gel to a membrane or filter can be designed tohold a gel cassette of a particular “standard” size in a bufferreservoir or tank, but can also hold a smaller than standard size gelcassette. In the context of electroblotting, a gel cassette is astructure having two sides that enclose a gel and a transfer membrane orfilter. The sides of an electroblotting cassette are porous, meshed,latticed, or otherwise permeable to fluid to allow the passage of bufferand electrical current from one side of the electroblot cassette,through the gel and transfer membrane, to the other side of theelectroblot cassette. In cases in which a smaller than standard sizecassette is used in the electroblotter, a buffer displacement dam can beinserted into the buffer tank to reduce the amount of buffer used duringelectrophoretic transfer.

In another example, an electrophoretic transfer apparatus that isdesigned for transferring biomolecules (such as but not limited toproteins or nucleic acids) from a gel to a membrane or filter can bedesigned to hold multiple gel cassettes in a buffer reservoir or tank,but can also hold fewer than the maximum number of gel cassettes it isdesigned to hold. In cases in which fewer than the maximum number ofcassettes are used in the electroblotter, a buffer displacement dam canbe inserted into the buffer tank to reduce the amount of buffer usedduring electrophoretic transfer. When inserted into the buffer tank ofan electroblotting apparatus, the buffer displacement dam can optionallyoccupy the space the position that would be taken by one or moreadditional cassettes, if the maximum number of cassettes were used inthe apparatus.

The present invention includes an electrophoretic transfer apparatusthat includes a buffer tank, in which the buffer tank comprises orcontacts two electrodes and comprises a buffer displacement dam and atleast one gel cassette that comprises a gel and a transfer membrane. Thebuffer displacement dam can displace at least 10%, preferably at least20%, and more preferably at least 30% of the volume of transfer bufferthat would otherwise be held by the buffer tank. In some embodiments,the displacement dam can displace 40% or more of the volume of transferbuffer that would otherwise be held by the buffer tank.

The invention also includes a method of electrophoretically transferringone or more biomolecules from a gel to a transfer membrane or filterusing a displacement dam in the buffer tank of an electrophoretictransfer apparatus, in which the electrophoretic transfer uses lesstransfer buffer that the maximum amount of buffer that can beaccommodated by the buffer tank. The method includes: positioning anelectrophoretic transfer gel cassette that comprises a gel containingone or more biomolecules and a transfer membrane in a buffer tank of anelectrophoretic transfer apparatus; inserting a buffer displacement daminto the buffer tank; adding transfer buffer to the buffer tank;connecting a power source to electrodes within or connected to thebuffer tank, and applying a voltage across the cassette to transferbiomolecules from the gel to the transfer membrane. The method uses lesstransfer buffer than would be used in the absence of a bufferdisplacement dam. The method can be used when a smaller cassette is usedthan the standard size accommodated by a transfer apparatus, or whenfewer than the maximal number of cassettes are used in the apparatus.The use of the displacement dam is not limited to these circumstances,however. In some cases, a buffer displacement dam can be used when lessthan maximal amounts of buffer are required based on electrophoreticconditions (buffer composition or applied voltage, e.g.).

A buffer displacement dam can be used in gel electrophoresisapparatuses. The electrophoresis apparatuses can be configured forhorizontal or vertical gel electrophoresis. A buffer displacement damcan be used in a cathode buffer reservoir, an anode buffer reservoir, orboth an anode buffer reservoir and a cathode buffer reservoir. The gelelectrophoresis apparatus can be used for the separation ofbiomolecules, such as but not limited to proteins, peptides, and nucleicacids.

In some preferred embodiments of the invention, a buffer dam is used inan electrophoresis apparatus that comprises one or more gel cassettes ina vertical orientation, each of which comprises a gel, in which one endof the gel contacts an “upper” buffer reservoir and the other end of thegel contacts a “lower” buffer reservoir. A displacement dam can be usedin the apparatus to take the place of one or more cassettes and/oradditional buffer reservoirs or buffer cores.

The present invention includes a buffer displacement dam for replacingelectrophoresis buffer in an electrophoresis apparatus having a tank, ananode reservoir, and a cathode reservoir, wherein the buffer damcomprises non-conductive material and is positioned within a tank of theelectrophoresis apparatus in a position otherwise occupied by a buffercore, such that less than 90%, and preferably less than 75%, of thebuffer is necessary within either the anode reservoir or the cathodereservoir compared to the amount of buffer required in the absence ofthe buffer displacement dam.

One configuration of a gel apparatus comprises a container into which isinserted multiple buffer cores, as depicted in FIG. 1. A gel cassette issealed to either side of a buffer core to form a buffer core assemblyhaving an internal space that serves as an “upper” buffer reservoir. Thearea of the container outside the buffer core assembly serves as the“lower” buffer reservoir. When fewer than the maximal number of buffercores are used in the apparatus, a buffer displacement dam can beinserted into the container to displace buffer that is not required whenrunning fewer than the maximal number of gels in the apparatus.

The buffer displacement dam takes up space in the container of theapparatus that would otherwise be taken up by “lower chamber” runningbuffer during use of the apparatus. In this way, the buffer displacementdam avoids the unnecessary use of large volumes of buffer when fewerthan the maximum number of gels that can be accommodated by the gelsystem are being run. In preferred aspects of the present invention, abuffer displacement dam can be used in a gel electrophoresis apparatusthat can accommodate multiple buffer cores, and the buffer displacementdam occupies at least a portion of the area that would otherwise betaken up by a buffer core, and further replaces volume in the containerthat would otherwise be taken up by buffer in the “lower reservoir”container (for example, anode buffer).

When the buffer displacement dam is positioned in the gel systemcontainer, it is not necessary that it form a seal against the containeror a buffer core element to prevent the passage of buffer from one areaof the container to another area of the container, because the damreduces the volume of buffer needed by replacing volume, rather than byblocking off an area of a buffer reservoir. Thus, in alternativeembodiments, a buffer displacement dam does not function as a dam, inthat it does not perform the function of sealing buffer within acompartment. A convenient feature of a preferred design of a bufferdisplacement device is that it need not be sealed to one or more wallsor edges of a buffer tank. This avoids the use of gaskets or othersealing components, fasteners, etc. A further advantage of this designtherefore is that only a single piece is required, and no assembly isperformed.

One example of a gel system that can accommodate multiple buffer coreassemblies and can use a buffer displacement dam is depicted in FIG. 7.The gel electrophoresis system (10) is made up of a container (212) intowhich two buffer core assemblies can be inserted. As shown, however, thecontainer (212) holds a single buffer core assembly (224) and a bufferdisplacement dam (203). The buffer displacement dam (203) conforms tothe internal dimensions of one end of the container (212), having fourwalls that define an interior space. Interior walls of which one isshown (205), provide structural support. The displacement dam (203) alsohas a lip (206) on the upper edge of one side to facilitate insertionand removal of the displacement dam.

FIG. 8 shows two views of a displacement dam shown separate from the gelelectrophoresis system. The displacement dam (203) is shown having fourwalls and a bottom, in which the protrusions (218) of one of the wallsdesigned to fit the internal dimensions of the container can be seen.

A buffer displacement dam for use in a gel electrophoresis system maybe, for example, from about 3 to about 30 inches in height, from about 3to about 20 inches in height, or preferably, from about 3 to about 10inches in height (depending on the height of the apparatus), morepreferably from about 3 to about 6 inches in height, more preferably yetfrom about 3.5 to about 5 inches in height, more preferably yet theheight is about 4.5 inches. A buffer displacement dam can be from about4 to about 40 inches in length, or preferably, from about 4 to about 30inches in length, or preferably, from about 4 to about 20 inches inlength, or preferably, from about 4 to about 10 inches in length, morepreferably from about 4 to about 8 inches in length, more preferably yetfrom about 3.5 to about 6.5 inches in length, more preferably yet thelength is about 6.14 inches. A buffer displacement dam can be from about1 to about 25 inches in width, or preferably, from 1 to about 20 inchesin width, or preferably, from 1 to about 15 inches in width, orpreferably, from 1 to about 10 inches in width, or preferably, fromabout 1 to about 5 inches in width, or preferably, from about 1 to about3 inches in width, or preferably, the buffer displacement dam is 1.66inches in width. The displacement dam can displace any amount of bufferfrom a buffer reservoir, for example, a volume of from about 50milliliters to about 1,500 milliliters, from about 100 milliliters toabout 1,500 milliliters, from about 200 milliliters to about 1,500milliliters, or from about 400 milliliters to about 1,000 milliliters.In one example of a buffer displacement dam for use in a midi gelapparatus, the displacement dam replaces from about 500 milliliters toabout 750 milliliters of buffer.

Such dimensions and parameters are examples only, as the design of thebuffer dam will vary to fit gel apparatus reservoirs in which they areused.

A multiple buffer core gel system can accommodate two, three, or morebuffer cores. In some exemplary examples in which a buffer displacementdam takes the place of a buffer core, the gel apparatus is designed toaccommodate two, buffer core assemblies. For example, the XCell4SureLock Midi-Cell, designed to run midi (approximately 8 cm×13 cm) gelsis an example of a multiple-core electrophoresis system in which adisplacement dam can be used. A displacement dam designed to fit theXCell4 SureLock Midi-Cell, as shown in FIGS. 7 and 8, has walls ofapproximately 4.5 inches in height, is about 6.14 inches in length, andis about 1.66 inches in width. The exemplary displacement dam replacesapproximately 675 milliliters of buffer.

In a gel system such as that depicted in FIG. 7, a buffer displacementdam can comprise a wall that can be engaged by a cam lock device forsealing at least one gel cassette to a buffer core in the containeroccupied by the displacement dam. The cam lock device can optionally bean expanding cam device, as described herein.

While at least one example embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexample embodiment or embodiments described herein are not intended tolimit the scope, applicability, or configuration of the invention in anyway. Rather, the foregoing detailed description will provide thoseskilled in the art with a convenient road map for implementing thedescribed embodiment or embodiments. It should be understood thatvarious changes can be made in the function and arrangement of elementswithout departing from the scope of the invention as set forth in theappended claims and the legal equivalents thereof.

All patents, patent publications, patent applications and otherpublished references mentioned herein are hereby incorporated byreference in their entirety as if each had been individually andspecifically incorporated by reference herein.

1-47. (canceled)
 48. A method for securing an electrophoresis gelcassettes in an electrophoresis container, the method comprising:providing a base plate having a first surface adapted to engage a buffercore assembly comprising the electrophoresis gel cassette; providing afollower plate having second surface adapted to engage a partitionassembly, the follower plate being slideably coupled to the base plate;providing a cam positioned between and moveably coupled with the baseplate and the follower plate; inserting the base plate, the followerplate and the cam between the buffer core assembly and the partitionassembly in the electrophoresis container; moving the cam from an openposition to a closed position to urge the first and second surfaces tosecure the gel cassettes to the first and second buffer core assemblies.49. The method of claim 48, wherein moving the cam to the closedposition causes the cam to lock the base plate and the following plateinto engagement with the gel cassettes of the first and second buffercore assemblies.
 50. The method of claim 48, wherein the partitionassembly comprises a buffer dam, a buffer displacement dam, or a buffercore assembly comprising at least one electrophoresis gel cassette. 51.The method of claim 50, wherein the partition assembly comprises abuffer core assembly comprising at least one electrophoresis gelcassette. 52-109. (canceled)